A. Field of the Invention
This invention relates to apparatus and methods for use with tissue expanders in the surgical treatment of skin lesions. In particular, this invention relates to use of ring-shaped tissue expanders which induce growth of skin in an annular geometry about a lesion so that on removal of the ring-shaped tissue expanders, the new skin contracts in radial directions to the center of the annulus to close the lesion.
B. Description of the Prior Art
It is a well known fact that skin and subcutaneous tissue expands. In medical practice, this physiological phenomenon is observed daily. Examples include skin progressively expanding over an underlying hematoma or a slowly growing tumor.
Providing extra skin tissue for reconstructive surgery by implanting an inflatable envelope connected to an external tube for injecting fluid into the envelope has been reported as early as 1957 (See, Neumann, C. G., The Expansion of an Area of Skin by Progressive Distention of the Subcutaneous Balloon, Plast.Reconstr.Surg., 19:124, 1957.) Substantial use of inflatable envelopes did not follow the work of Neumann.
In the mid-1970's, however, Dr. Chedomir Radovan disclosed an implantable, inflatable envelope for inducing growth of new skin with a semi-rigid backplate attached to the expandable envelope and a connected self-sealing remote injection port (See, e.g., U.S. Pat. No. 4,217,889, entitled Flap Development Device and Method of Progressively Increasing Skin Area, issued Aug. 19, 1980 to Chedomir Radovan, and Rudolf R. Schulti; and Radovan, C. Reconstruction of the Breast after Radical Mastectomy Using Temporary Expander, Plast.Surg.Forum, 1:41, 1978). Subsequent to Radovan's work, Eric Austad developed self-inflating soft tissue expanders having permeable envelopes enclosing a high solute load. By osmosis the solute is diluted by body fluids which causes a slow expansion without the need for periodic injections (See, U.S. Pat. No. 4,157,085 entitled Surgically Implantable Tissue Expanding Device and the Method of its Use, issued Jun. 5, 1979 to Eric Austad).
The use of inflatable envelopes to induce growth of new skin and subcutaneous tissue has been found useful in surgical breast reconstruction, and for providing adjacent skin flaps for use in plastic surgery and in the surgical removal of tattoos, benign processes such as lymphangiomes and large scars. Having new skin and subcutaneous tissue grown for use adjacent to the area of growth has the advantages of providing essentially identical skin which matches both the skin color and texture of the skin in the area to be healed. This degree of skin matching is not always achieved in skin grafting where skin is taken from a different part of a patient and transplanted to a second location.